@inbook {KNZ001114,
	title = {Ecological consequences of the replacement of native grassland by Juniperus virginiana and other woody plants},
	booktitle = {Ecological Studies Vol. 196, Western North American Juniperus communities: A dynamic vegetation type},
	year = {2008},
	pages = {156 -169},
	publisher = {Springer-Verlag, NY},
	organization = {Springer-Verlag, NY},
	abstract = {<p>Although grasslands have been altered by humans for thousands of years (Wedel 1961; Bond et al. 2003), the loss of grassland as a result of anthropogenic activities has increased dramatically over the past 150 years. When Europeans first settled the Midwest and Great Plains, the greatest threat to native grasslands was the conversion of the most highly productive of these ecosystems to row-crop agriculture (Samson and Knopf 1994). Later, with improvements in soil moisture management and irrigation technology, even low-productivity grasslands were plowed. Today, those remnants of the most productive grasslands that escaped the plow are threatened, as are most of Earth\&rsquo;s ecosystems, by a variety of global change phenomena (Vitousek et al. 1997), with the invasion and expansion of woody species into grasslands one of the greatest of these threats. The replacement of grasslands by shrubland, woodland, and forest is a concern not only in the United States but worldwide (Archer et al. 1988; Van Auken 2000; Roques et al. 2001; Silva et al. 2001). Species of woody plants that invade grasslands may include both native plants which previously existed as more minor components of the ecosystem as well as alien species (Bragg and Hulbert 1976; Harcombe et al. 1993).</p>},
	keywords = {LTER-KNZ},
	doi = {10.1007/978-0-387-34003-6_8},
	url = {https://link.springer.com/chapter/10.1007\%2F978-0-387-34003-6_8},
	author = {Alan K. Knapp and McCarron, J.K. and Silletti, A.M. and Hoch, G.A. and Heisler, J.L. and Lett, M.S. and John M. Blair and J. M. Briggs and M.D. Smith},
	editor = {Van Auken, O.W.}
}
@article {KNZ00894,
	title = {Competition and coexistence in grassland co-dominants: responses to neighbor removal and resource availability},
	journal = {Canadian Journal of Botany},
	volume = {82},
	year = {2004},
	pages = {450 -460},
	abstract = {We examined the role of interspecific competition in the regulation of abundance and coexistence of the dominant grasses in tallgrass prairie using a removal experiment with Andropogon gerardii Vitman and Sorghastrum nutans L. Nash, two of the most abundant grasses in tallgrass prairie. Plant removal treatments (using foliar herbicide), applied to 0.3-m2 plots at the Konza Prairie Biological Station (northeast Kansas, USA), included removal of all A. gerardii, removal of all S. nutans, and no removal. To determine whether soil fertility altered the outcome, we included a fertilizer addition treatment (10 g N{\textperiodcentered}m2) fully crossed with the removal treatments. Andropogon gerardii removal resulted in significantly increased net photosynthesis, stomatal conductance, and tiller mass in S. nutans. Sorghastrum nutans removal had little effect on A. gerardii, suggesting asymmetric competition. Fertilizer significantly increased tiller mass and flowering stalk production in S. nutans, but had little effect on A. gerardii. The ability of A. gerardii to suppress the performance of S. nutans is consistent with the greater abundance of A. gerardii over much of the tallgrass prairie, while the ability of S. nutans to take advantage of increased resources may be one mechanism by which it avoids competitive exclusion. Because of the greater variability in the performance of S. nutans than in that of A. gerardii, any natural or anthropogenic alterations to this grassland that lead to shifts in dominance between these species may affect ecosystem productivity and stability.Key words: Andropogon gerardii, competition, grassland, neighbour removal, photosynthesis, Sorghastrum nutans, tallgrass prairie.},
	keywords = {LTER-KNZ},
	doi = {10.1139/b04-016},
	author = {Silletti, A.M. and Alan K. Knapp and John M. Blair}
}
@article {KNZ00826,
	title = {Long-term responses of the grassland co-dominants Andropogon gerardii and Sorghastrum nutans to changes in climate and management},
	journal = {Plant Ecology},
	volume = {163},
	year = {2002},
	pages = {15 -22},
	abstract = {Understanding responses of both dominant and sub-dominant plant speciesto management regimes and climatic variables is a critical component ofunderstanding an ecosystem{\textquoteright}s potential response to local or regional changes insuch parameters. The dominant vegetation of much of the North Americantallgrassprairie is composed of C4 grasses. As the most abundant species,Andropogon gerardii has been well characterizedecologically. The second most abundant, co-dominant species,Sorghastrum nutans, has received less attention, mainlybecause it has been considered the {\textquotedblleft}ecological equivalent{\textquotedblright} ofA. gerardii and is assumed to have responses similar tothose of A. gerardii. The objective of this study was toassess the validity of this assumption by examining long-term abundancepatternsand responses to climate, fire, and grazing for both species. Based on 15 years(1983{\textendash}1997) of plant species composition and cover data collected atKonzaPrairie Biological Station in northeastern Kansas, USA, we were able to detectimportant differences between these two grasses. Regression analysis showedthatlong-term reductions in the cover of A. gerardii werecorrelated with decreasing summer maximum temperatures, whereas inter-annualvariations in the cover of S. nutans were related toannualprecipitation. Additionally, the cover of S. nutansincreased with increasing fire frequency, while the cover of A.gerardii was not significantly affected by fire frequency. Bisongrazing did not significantly affect the cover of either species studied. Themean cover of A. gerardii decreased significantly over the15 years, but only a slight change was noted in the cover of S.nutans. The decrease in A. gerardiicorrespondedto increased plant species diversity and evenness and has the potential toimpact the tallgrass prairie ecosystem from population through ecosystemlevels.The observed differences in these co-dominant species may prove important underclimate change scenarios predicted for the tallgrass prairie of North America.},
	keywords = {LTER-KNZ, C4 grasses, Cover, diversity, Dominance, fire, prairie, tallgrass},
	doi = {10.1023/A:1020320214750},
	author = {Silletti, A.M. and Alan K. Knapp}
}
@article {KNZ00787,
	title = {Responses of the co-dominant grassland species Andropogon gerardii and Sorghastrum nutans to long-term manipulations of nitrogen and water},
	journal = {American Midland Naturalist},
	volume = {145},
	year = {2001},
	pages = {159 -167},
	abstract = {The availability and distribution of essential resources such as water and nitrogen are changing on a global scale and it is important to determine the effects of such alterations on dominant and subdominant species in ecosystems. We examined the effects of long-term additions of water and nitrogen on leaf-level ecophysiological characteristics of the tallgrass prairie codominants Andropogon gerardii (big bluestem) and Sorghastrum nutans (Indian grass). Both species responded to irrigation with increased water potentials and to fertilization with decreased water potentials. Only in S. nutans, however, were net photosynthesis and stomatal conductance greater in response to both water and nitrogen addition. In contrast, A. gerardii, which currently is more abundant than S. nutans, was relatively unresponsive to resource manipulations. If net photosynthesis is positively related to plant productivity, as has been shown for tallgrass prairie species, the differential photosynthetic responses of these two grasses suggests that their patterns of abundance may change in the future if resource availability is altered. These results are also inconsistent with the historical assumption that these two grasses are {\textquotedblleft}ecological equivalents.{\textquotedblright}},
	keywords = {LTER-KNZ},
	doi = {10.1674/0003-0031(2001)145[0159:ROTCGS]2.0.CO;2},
	author = {Silletti, A.M. and Alan K. Knapp}
}
@mastersthesis {KNZ00748,
	title = {Comparative ecology of the C4 grassland co-dominants Andropogon gerardii  and Sorghastrum nutans},
	volume = {MS Thesis},
	year = {2000},
	pages = {1 -85},
	school = {Kansas State University},
	type = {M.S. Thesis},
	address = {Manhattan, KS},
	keywords = {LTER-KNZ},
	author = {Silletti, A.M.}
}
